Drought is one of the major limiting factors for plant productivity and spatial distribution. The annual loss in yield of major cereal crops due to drought is estimated to exceed ten billion dollars globally. Furthermore, desertification, defined as “Land degradation in arid, semi-arid and dry sub-humid areas,” is happening in about 70% of the total drylands (3.6 billion hectares) of the world and has become a very distinctive global issue with major environmental consequences. It affects about 25% of the total land area of the world and about 17% of the world population. Development of drought-tolerant plant species represents a promising strategy to tackle these problems. Conventional crop improvement for enhanced drought tolerance has been ineffective, mainly due to limited germplasm resources and incompatibility in crosses between distantly related plant species. Recent advances in plant gene discovery and genetic transformation paved the road to generate stress-tolerant crops using transgenic approaches.
Despite the enormous economic and environmental significance, identification and characterization of plant genes that confer drought tolerance remains a challenge.